How not to get first names (neither full nor abbreviations) in in-text citations?

Question

I need to conform my citations with the format my lecturer wants. I was told to never have the first names in an in-text citation. In case there are several authors with the same last name, they should be distinguished by a letter behind the year. The citation style is author year; I'm using biblatex like this atm: \usepackage[ backend=biber, style=authoryear, natbib=true ]{biblatex}

Answer 1

I found out that uniquename=false removes the first names of the authors. However, I am not sure whether the citations are unique in any case. I guess it's all fine as long as authors with the same name didn't publish in the same year.